Scrambling for lightweight censorship resistance (transcript of discussion)

Abstract

Hello everyone, today I will talk about new ideas about censorship resistance. First of all, what threat models are we assuming, and what kind of censors are we talking about. In this paper we are assuming a passive global censor, that basically means there is some well-founded organization who would be able to sit at the backbone of some internet communication, possibly on the outgoing router of some internet infrastructure, and watch all communication going in and out of the domain. And what they do is, they will inspect the packet contents, possibly deep-packet inspection on the TCP session, etc, and detect any content which is in blacklist. If any of the blacklisted keywords is being detected in that TCP session, then the adversary will try to block the connection by various means. What the censor will not do is trying to actively modify the communication channel, it will only observe passively. One readily available example in the real world is the Great Firewall project of the Chinese government. Basically it observes all traffic goes in and out of China, uses deep-packet inspection techniques to detect any blacklist keywords, and if any of them is detected then it will inject a malformed packet to disrupt the TCP session, and cause the connection to reset. © 2011 Springer-Verlag.